feat: implement blob streaming in the aggregator by slivers

[wbbradley]

Description

Implement streaming blobs by slivers via a new endpoint /v1/blobs/{blob_id}/stream.

Test plan

Manually tested. CI Pipeline.

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Release notes

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• Storage node:
• Aggregator: There is a new alpha endpoint /v1alpha/blobs/{blob_id}/stream which is intended to reduce latency to first byte, and is intended to be used to stream blob data.
• Publisher:
• CLI:

[github-actions]

Warning: This PR modifies one of the example config files. Please consider the
following:

• Make sure the changes are backwards compatible with the current configuration.
• Make sure any added parameters follow the conventions of the existing parameters; in
  particular, durations should take seconds or milliseconds using the naming convention
  _secs or _millis, respectively.
• If there are added optional parameter sections, it should be possible to specify them
  partially. A useful pattern there is to implement Default for the struct and derive
  #[serde(default)] on it, see BlobRecoveryConfig as an example.
• You may need to update the documentation to reflect the changes.

[jpcsmith]

Removed myself since Markus is having a look. Let me know if there something that I should look at regardless.

[halfprice]

Thanks @wbbradley for implementing this feature! This looks great and I only have some minor comments.

Another thing we discussed was to use streaming blob as default and replace the existing blocking get_blob. Can you create a issue tracking this?

[wbbradley]

@halfprice I believe I've addressed your comments. I've also implemented a new e2e test called test_streaming_blob.

[wbbradley]

I've added WAL-1107 to track using this functionality for get_blob.

[halfprice]

Looks great! Thanks @wbbradley for adding this.